Create Projection

Creates a new projection of an existing table. A projection represents a subset of the columns (potentially including derived columns) of a table.

For projection details and examples, see Projections. For limitations, see Projection Limitations and Cautions.

Window functions, which can perform operations like moving averages, are available through this endpoint as well as Get Records by Column.

A projection can be created with a different shard key than the source table. By specifying shard_key, the projection will be sharded according to the specified columns, regardless of how the source table is sharded. The source table can even be unsharded or replicated.

If input parameter table_name is empty, selection is performed against a single-row virtual table. This can be useful in executing temporal (NOW()), identity (USER()), or constant-based functions (GEODIST(-77.11, 38.88, -71.06, 42.36)).

Input Parameter Description

NameTypeDescription
table_namestringName of the existing table on which the projection is to be applied, in [schema_name.]table_name format, using standard name resolution rules. An empty table name creates a projection from a single-row virtual table, where columns specified should be constants or constant expressions.
projection_namestringName of the projection to be created, in [schema_name.]table_name format, using standard name resolution rules and meeting table naming criteria.
column_namesarray of stringsList of columns from input parameter table_name to be included in the projection. Can include derived columns. Can be specified as aliased via the syntax 'column_name as alias'.
optionsmap of string to strings

Optional parameters. The default value is an empty map ( {} ).

Supported Parameters (keys)Parameter Description
create_temp_table

If true, a unique temporary table name will be generated in the sys_temp schema and used in place of input parameter projection_name. If persist is false (or unspecified), then this is always allowed even if the caller does not have permission to create tables. The generated name is returned in qualified_projection_name. The default value is false. The supported values are:

  • true
  • false
collection_name[DEPRECATED--please specify the containing schema for the projection as part of input parameter projection_name and use Create Schema to create the schema if non-existent] Name of a schema for the projection. If the schema is non-existent, it will be automatically created. The default value is ''.
expressionAn optional filter expression to be applied to the source table prior to the projection. The default value is ''.
is_replicated

If true then the projection will be replicated even if the source table is not. The default value is false. The supported values are:

  • true
  • false
offsetThe number of initial results to skip (this can be useful for paging through the results). The default value is '0'.
limitThe number of records to keep. The default value is '-9999'.
order_byComma-separated list of the columns to be sorted by; e.g. 'timestamp asc, x desc'. The columns specified must be present in input parameter column_names. If any alias is given for any column name, the alias must be used, rather than the original column name. The default value is ''.
chunk_sizeIndicates the number of records per chunk to be used for this projection.
chunk_column_max_memoryIndicates the target maximum data size for each column in a chunk to be used for this projection.
chunk_max_memoryIndicates the target maximum data size for all columns in a chunk to be used for this projection.
create_indexesComma-separated list of columns on which to create indexes on the projection. The columns specified must be present in input parameter column_names. If any alias is given for any column name, the alias must be used, rather than the original column name.
ttlSets the TTL of the projection specified in input parameter projection_name.
shard_keyComma-separated list of the columns to be sharded on; e.g. 'column1, column2'. The columns specified must be present in input parameter column_names. If any alias is given for any column name, the alias must be used, rather than the original column name. The default value is ''.
persist

If true, then the projection specified in input parameter projection_name will be persisted and will not expire unless a ttl is specified. If false, then the projection will be an in-memory table and will expire unless a ttl is specified otherwise. The default value is false. The supported values are:

  • true
  • false
preserve_dict_encoding

If true, then columns that were dict encoded in the source table will be dict encoded in the projection. The default value is true. The supported values are:

  • true
  • false
retain_partitions

Determines whether the created projection will retain the partitioning scheme from the source table. The default value is false. The supported values are:

  • true
  • false
partition_type

Partitioning scheme to use.

Supported ValuesDescription
RANGEUse range partitioning.
INTERVALUse interval partitioning.
LISTUse list partitioning.
HASHUse hash partitioning.
SERIESUse series partitioning.
partition_keysComma-separated list of partition keys, which are the columns or column expressions by which records will be assigned to partitions defined by partition_definitions.
partition_definitionsComma-separated list of partition definitions, whose format depends on the choice of partition_type. See range partitioning, interval partitioning, list partitioning, hash partitioning, or series partitioning for example formats.
is_automatic_partition

If true, a new partition will be created for values which don't fall into an existing partition. Currently only supported for list partitions. The default value is false. The supported values are:

  • true
  • false
view_idID of view of which this projection is a member. The default value is ''.
strategy_definitionThe tier strategy for the table and its columns.
join_window_functionsIf set, window functions which require a reshard will be computed separately and joined back together, if the width of the projection is greater than the join_window_functions_threshold. The default value is 'true'.
join_window_functions_thresholdIf the projection is greater than this width (in bytes), then window functions which require a reshard will be computed separately and joined back together. The default value is ''.

Output Parameter Description

NameTypeDescription
projection_namestringValue of input parameter projection_name.
infomap of string to strings

Additional information. The default value is an empty map ( {} ).

Possible Parameters (keys)Parameter Description
countNumber of records in the final table
qualified_projection_nameThe fully qualified name of the projection (i.e. including the schema).